1. Field of the Invention
The invention relates to positioning mechanisms for sliding devices and, more specifically, relates to positioning mechanisms using a spring.
2. Description of Related Art
The use of devices which have two connected parts that slide relative to one another has become increasingly popular in the portable electronics industry. Typically, a top member slides over a bottom member in moving between an open position and a closed position. In the closed position a first surface on the front of the top member is viewable but a second surface on the front of the bottom surface is concealed. When opened, the top member slides away, exposing, the second surface of the bottom member. This arrangement has several advantageous characteristics. First, the second surface increases the viewable and usable surface area of the device. Second, the device can be placed in the closed position to make it more compact. Finally, the second surface is protected when in the closed position, allowing sensitive components to be placed thereon without the risk that they will be affected when the device is closed.
Commonly, sliding electronic devices include a screen on the first surface and a keypad on the second surface. The screen is always exposed and viewable such that it may be read without opening the device. On the other hand, the keypad is only exposed when the device is opened. Thus, the keypad is protected when the device is not being used.
It is usually desirable to have sliding devices of this kind be fixed in the open position or in the closed position. It is undesirable for the user to be required to hold the device in the open position while using both the first and second surface. Likewise, when the device is stored away it is advantageous for the device to remain in the closed position.
Accordingly, most sliding devices have a locking mechanism that holds the sliding device in one of the open position and the closed position, but is weak enough that the user can easily change the position of the device by applying a slight pressure. Known locking mechanisms include systems having a ball, groove and two catches. The ball is held in place with respect to one of the top or bottom member, and the other member includes the groove with the catches at either end of the groove. If the device is closed the ball rests in one catch. When the user pushes the top member over the bottom member, the ball is dislodged from the catch and rolls along the groove until it lodges into the other catch. A similar design includes spring loaded protrusions on one of the members at both ends of a groove or path. A wedge on the other member is disposed in the path such that it sits behind the protrusion when in either the open or closed position. When the user pushes the slide, the wedge forces the protrusion back and slides along the path until it becomes fixed behind the protrusion at the other end of the path. Both of these mechanisms operate adequately, however, they include a number of small precision parts.
Another known locking mechanism includes magnets that hold the sliding members at either end. This mechanism is effective, but can interfere with the electronics of the device and thus, requires shielding.
Another drawback of these locking mechanisms is that they all require the user to operate the sliding device until it has locked in one of the open or closed positions. If the user slides the members almost all the way to the locked position, but does not lock the device, there is a risk that the device will slide back to the previous position. Thus, there is a need for a simple, low-cost mechanism that will hold a sliding device in two positions.